Cytokeratin 8 (CK8) and vimentin are co-expressed in some bovine nucleus pulposus (NP)-derived cells. Higher-resolution images showing dual-immunofluorescence staining of CK8 and vimentin (VIM) on freshly isolated NP and notochordal cells. Cells were also imaged under classical phase-contrast microscopy (PHASE), and nuclei were visualized with DAPI (4'-6-diamidino-2-phenylindole) (scale bar = 10 μm). Clusters of bovine NP (a), readily visible as separate cells under PHASE, and of much larger porcine cells (b) both co-expressed VIM and CK8 (c,d). However, the organization of these microfilaments appears to differ between the two cell types, being more uniform in the bovine cells (e,f) and mainly concentrated toward the plasma membrane in the porcine cells (g,h).